What Happened Here? .308 case ribbed

Anyone care to guess what happened to these, .308 Federal Case. They were picked up at the range and feel as if they were fire formed to a chamber with rifling's cut in. They were also very sooty all over as you can see in the rim and neck area. They were nearly completely black from soot.

Hi, it looks like these we're fired in a fluted chamber , fluted chambers we're used to ease extraction in some semi auto's I think I'm right in saying that the old squeeze cock H&K 9mm pistols had these but it's been so long since our idiot government banned handguns that the old memory is starting to fade........

watch your new government closely and vigourously fight any changes they propose , and above all stick together . we lost handguns largly due to the we're alright attitude from our very own NRA !